Try to install a plugin in PluginManager; click "Install and restart".
in UpdateCenter, screen stuck at "Preparation Checking internet connectivity".

No logs printed out in `var/log/jenkins/jenkins.log`

This bug is caused by method `getConnectionCheckUrl` using url "google.com" to check connectivity.
https://github.com/jenkinsci/jenkins/blob/afd8da49901775900a80eb2b2a9746b01156b0ba/core/src/main/java/hudson/model/UpdateCenter.java#L841

------- update:
I just built jenkins.war replaced the google.com with another url. But It still not work.

I got these warnings, and the log is the same when using 'google.com' url. So it may not be the url problem.

七月 02, 2014 7:49:14 下午 hudson.model.UpdateSite$Plugin deploy
警告: Adding dependent install of ssh-credentials for plugin git
七月 02, 2014 7:49:14 下午 hudson.model.UpdateSite$Plugin deploy
警告: Adding dependent install of credentials for plugin ssh-credentials
七月 02, 2014 7:49:14 下午 hudson.model.UpdateSite$Plugin deploy
警告: Adding dependent install of git-client for plugin git
七月 02, 2014 7:49:14 下午 hudson.model.UpdateSite$Plugin deploy
警告: Dependent install of ssh-credentials for plugin git-client already added, skipping
七月 02, 2014 7:49:14 下午 hudson.model.UpdateSite$Plugin deploy
警告: Adding dependent install of scm-api for plugin git
七月 02, 2014 7:49:14 下午 hudson.model.UpdateSite$Plugin deploy
警告: Dependent install of credentials for plugin git already added, skipping